1. Field of the Invention
The present invention relates to a method for positioning the dies set to a stationary platen and a movable platen of a plastic molding machine such as an injection molding machine and a temporarily clamping apparatus used for the method.
2. Background Art
In general, one of the dies is set to a movable platen before the other is set to a stationary platen. The die is secured to the stationary platen with bolts at four places or by setting clamps at four places: right and left and top and bottom of a die mounting plate, one each, and fastening the die with the clamps.
Even when the dies are secured to their home position, imperfect die closing may occur due to a slight deviation between the dies. Therefore, it is necessary to perform the positioning of the dies before setting them.
The positioning is performed for the die of the stationary platen side. In most cases, the positioning is performed by slightly loosening the bolts or clamps securing the die and temporarily setting the die to the home position to provide the die with a margin in the lateral direction before performing die matching.
For the above positioning method, however, it is difficult to adjust the die fastening degree. If the fastening for temporary setting is insufficient, die matching is difficult because the die is deviated extremely lower than the home position. If the fastening is excessive, the die easily moves in the lateral direction. Therefore, galling occurs due to imperfect die matching and the die may be broken in the worst case.
Especially for a die to be closed by fitting the straight surface of it to a spigot, a clearance is provided to prevent the fitting portion from being abraded when the die is opened or closed. For the existing method, however, positioning is very troublesome and requires a long time because the clearance is very small. Therefore, for a small volume production requiring frequent replacement of dies, there is a problem in that the positioning causes the productivity to decrease.